2 custodians found shot dead inside Chicago elementary school, police say

Two school custodians have been found shot dead in a Chicago elementary school, according to Chicago ABC station WLS.

The 48-year-old woman and the 63-year-old man were found Monday afternoon at Mark Twain Elementary School, both with single gunshot wounds to the head, Chicago police said.

Both were in critical condition when taken to a hospital where they were pronounced dead, police said.

A weapon was recovered at the scene, police said.

School principal Matthew Moline said no students were in the building at the time.

Moline didn't identify the victims, but said in a letter to the school community that "members of our school community were impacted."

"We will work to provide additional information to the school community as the investigation proceeds," Moline said. "Please know that we are taking this situation very seriously."

Trumaine Reeves, Executive Vice President of the SEIU Local 73 union, which represents custodial staff, said in a statement, "The only facts we know right now are that two families have lost a loved one and our prayers are with their families, and the staff, students, and families at Mark Twain Elementary School."

ABC News' Alex Fine and Darren Reynolds contributed to this report.